1. Field of the Invention
The present invention relates to an article entirely covered with a tube, a tubular cover member for covering an article with a tube useful for producing such an article, and a method of covering an article with a tube. The present invention can be advantageously used for, for example, insulation and protection (waterproofing, oil-proofing, etc.) of a long article such as cables and cords, and rust prevention, corrosion prevention, or impact relaxation of tubes, cables, or wire harnesses of automobiles, electrical appliances or the like.
2. Description of the Related Art
Use of various room temperature shrink type tubes has heretofore been proposed for insulation treatment of wires and cables, rust prevention and impact relaxation treatments of metal pipes, or the like treatments. A room temperature shrink tube designates a tube that can be shrunk to have a desired shape at room temperature, namely, without heat treatment by mounting the tube on the periphery of a core such as a hollow cylinder in a pre-stretched state, and withdrawing the core. The tube is also termed a pre-stretched tube (PST).
For example, Japanese Unexamined Utility Model Publication (Kokai) No. 6-84754 discloses, as schematically shown in FIG. 1, a room temperature recoverable tube 50 characterized in that a radially expanded elastic tube 54 is mounted on a spacer 53 formed by detachably connecting two hollow cylinders each having a flange portion 51 at one end, approximately in the central portion. The room temperature recoverable tube is designed in such a manner that the hollow cylinders are separated by grasping both flange portions and pulling them after setting the room temperature shrink tube on wires, etc. The elastic tube shrinks from the central portion toward both ends, and can be mounted on wires, etc. when the spacer is removed from the elastic tube.
A similar room temperature shrink tube is disclosed as a self-recoverable tube in Japanese Unexamined Utility Model Publication (Kokai) No. 7-18831. The self-recoverable tube is characterized in that an elastic rubber or plastic tube is mounted on the cylindrical portion of a hollow cylindrical body provided with a flange portion at one end, an expansion portion at the other end, and a slit in the axial direction at the circumference while the tube is expanded to have a diameter larger than the maximum outer diameter of the expansion portion and suitably creased.
For the room temperature recoverable tube disclosed in Japanese Unexamined Utility Model Publication (Kokai) No. 6-84754, when the elastic tube is to be mounted on the hollow cylindrical body, the tube having a length approximately twice as large as the length of the cylindrical body can be mounted by forming creases in the tube in a bellows-like form. However, the method requires a cylindrical body that can be separated into two each having a flange portion at the end. The production of the cylindrical body therefore requires a complicated mold, and a cost increase in the production cannot be avoided. Moreover, since the structure of the cylindrical body is complicated, the method has the disadvantage that the cylindrical body having been used is difficult to withdraw from the tube after positioning inside the tube. In order to make the withdrawing operation easy, the interface between the cylindrical body and the tube is coated with a lubricant. However, since the lubricant remains on the inner surface of the tube after shrinking the tube, the method cannot be recommended in view of the adverse effects of contamination, by lubricant transfer to the wires, etc.
Moreover, for a self-recoverable tube disclosed in Japanese Unexamined Utility Model Publication (Kokai) No. 7-18831, provision of a slit in the axial direction at the circumference of the hollow cylindrical body makes the operation for withdrawing the cylindrical body easy after mounting the shrink tube. However, since the cylindrical body used herein also has a complicated structure, there still remains a room for improvement in the production cost and operation for withdrawing the cylindrical body.
Furthermore, there is a problem common to the above two types of room temperature recoverable tubes, namely, a problem about the flange portions to be attached to the end portions of the hollow cylindrical body. Since the flange portion is significantly large in comparison with the size of the cylindrical body, an ample space for mounting the flange portion on wires, etc. must be ensured in advance. That is, the sites to which the room temperature shrink tube can be applied are markedly restricted.
Incidentally, the applicant of this application has proposed, as disclosed in, for example, Japanese Examined Patent Publication (Kokoku) No. 49-46190, the use of a hollow cylindrical body having a continuous spiral groove formed on the wall surface over the entire length in order to make easy the operation of withdrawing the hollow cylindrical body used as a core. That is, since the core proposed herein is formed by separably and spirally bonding a strip-like piece, the core can be easily withdrawn by successively peeling the strip-like piece from the end portion, and the production cost can be reduced. However, when a long room temperature recoverable product using the core is to be provided, a long core having a length in accordance with that of the product must be prepared. As a result, the use of the product requires not only a wide storage space but also a wide operation space. Moreover, when the core is long, the operation of separating the strip-like piece and withdrawing it requires much time and labor.
An object of the present invention is to solve the problems associated with the prior art explained above, and provide a tube-covered article that is a long article entirely covered with a room temperature shrink type tube, that can be easily produced at low cost because the structure of the production tubular cover member is simple, and that requires no lubricant between the article and the tube.
Another object of the present invention is to provide a tubular cover member for covering an article with a tube that is useful for producing the tube-covered article of the invention, that has a simple structure, that can be stored and operated in narrow spaces, and that is excellent in operability.
Still another object of the present invention is to provide a method of covering an article with a tube that is useful for producing the tube-covered article of the invention and excellent in operability and that uses no lubricant.
The objects explained above and other objects will be easily understood from the detailed explanation made below.